It says instance requirements so if you try to receive a summon to dungeon which level is 64 and you are 61 i think you can’t get it? If i read right what you wrote in the OP.
Bazsul literally gave you the answer 2nd post. We’re playing “2.4.3”, but that’s just mainly for classes balance. We’re not at 2.4.3 content, that’s getting delievered same timeline as it did back in original TBC. So we won’t be able to summon people into instances for a while yet. So all though we’re in 2.4.3, we don’t have the 2.4.3 content yet, and some of the changes we should have in it like LFG/summon to instances etc.
You will not be able to summon inside instances or in Netherstorm until a later phase. Check the Blue’s text with the patch notes they implemented in the Beta.